Bombesin and somatostatin (somatostatin analogs) act within the central nervous system (CNS) to alter body temperature (TB). Studies are proposed to evaluate the physiologic participation of these peptides in CNS regulation of TB. The site(s) of action of bombesin and somatostatin within the CNS to influence TB will be determined following microinjection of peptides into various brain regions. The anterior hypothalamic preoptic area has already been demonstrated to be one site of bombesin action of TB. Correlation of site of action of bombesin and somatostatin with their respective anatomic and receptor distribution will be achieved using radioimmunoassay, immunohistochemical, membrane receptor assay and autoradiographic methods. The mechanisms of change in TB induced by bombesin and somatostatin will be assessed using indirect calorimetry. Involvement of bombesin or somatostatin in physiologic regulation of TB will be assessed using specific peptide antagonists, passive immunizaiion and desensitization methods. Using these methods we will determine if bombesin or somatostatin mediate the adaptive hypothermia in insulin, 2-deoxy-glucose treated or fasted animals. These various studies will provide fundamental information regarding the thermoregulatory and general neurobiological role of peptides. These new insight into neurobiology will undoubtedly lead to advances in clinical management of disorders of thermoregulation.